(a) Field of the Invention
The present invention relates to a method and an apparatus of controlling an output voltage of a direct current (DC) converter for a vehicle that has a driving motor.
(b) Description of the Related Art
Generally, a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), an electric vehicle, and a fuel cell electric vehicle (FCEV) commonly called an environmental-friendly vehicles are driven by a driving motor that obtains a torque by electrical energy. Particularly, the hybrid electric vehicle efficiently combines and uses power of an internal combustion engine and power of the driving motor.
The environmental-friendly vehicle drives the driving motor using a voltage of a main battery (e.g., high voltage battery) and drives an electric load using a voltage of an auxiliary battery (e.g., low voltage battery). The electric load includes electric or electronic apparatuses using the voltage of the auxiliary battery, such as a head lamp, an air conditioner, a wiper, and the like. To convert a high voltage supplied from the main battery into a low voltage and supply the low voltage as an operation voltage to the electric load using the low voltage, a low voltage DC-DC converter (LDC) is disposed between the main battery and the auxiliary battery.
The environmental-friendly vehicle according to the related art adjusts an output voltage of the LDC based on a current driving mode and a state of charge (SOC) of the auxiliary battery to charge or discharge of the auxiliary battery. According to a method of adjusting (e.g., controllering) the output voltage of the LDC according to the related art, the auxiliary battery may be efficiently charged or discharged at a current time. However, since the method of controlling the output voltage of the LDC according to the related art does not completely reflect conditions of a road (e.g., a change in a gradient of the road, a change in a curvature radius of the road, and the like), it is inefficient in consideration of an entire driving section. For example, when entering a downhill and, when the SOC of the auxiliary battery is high, a chargeable SOC is insufficient, thus wasting regenerative braking energy.
The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.